Reaction rates and dissolution mechanisms of quartz as a function of pH

Shikha Nangia, Barbara J. Garrison

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

In this computational study, we present the dissolution rates for quartz as a function of pH at 298 K. At any given pH, the dissolution of the quartz surface depends on the distribution of protonated, deprotonated, or neutral species. The dissolution mechanism for each of these three species was investigated by ab initio electronic structure calculations to obtain the reaction profile. Using the barrier height along with the partition functions for the transition state and the reactants in the rate-limiting steps, we calculated the TST rate constants for the reactions for the temperature range of 200-500 K. At 298 K the rate constant (s-1) for the dissolution of neutral species was found to be several orders of magnitude smaller than the rate-limiting steps for the protonated and deprotonated species. The values of the rate constants were used in the rate law expression to calculate the overall dissolution rate (mol m-2 s-1) at a given pH. The calculated rates were compared to previously reported experimental and theoretical rates and were found to be in good agreement over 2-12 pH range.

Original languageEnglish (US)
Pages (from-to)2027-2033
Number of pages7
JournalJournal of Physical Chemistry A
Volume112
Issue number10
DOIs
StatePublished - Mar 13 2008

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Quartz
Reaction rates
dissolving
Dissolution
reaction kinetics
quartz
Rate constants
Electronic structure
partitions
electronic structure
Temperature

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry

Cite this

Nangia, Shikha ; Garrison, Barbara J. / Reaction rates and dissolution mechanisms of quartz as a function of pH. In: Journal of Physical Chemistry A. 2008 ; Vol. 112, No. 10. pp. 2027-2033.
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Reaction rates and dissolution mechanisms of quartz as a function of pH. / Nangia, Shikha; Garrison, Barbara J.

In: Journal of Physical Chemistry A, Vol. 112, No. 10, 13.03.2008, p. 2027-2033.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Reaction rates and dissolution mechanisms of quartz as a function of pH

AU - Nangia, Shikha

AU - Garrison, Barbara J.

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N2 - In this computational study, we present the dissolution rates for quartz as a function of pH at 298 K. At any given pH, the dissolution of the quartz surface depends on the distribution of protonated, deprotonated, or neutral species. The dissolution mechanism for each of these three species was investigated by ab initio electronic structure calculations to obtain the reaction profile. Using the barrier height along with the partition functions for the transition state and the reactants in the rate-limiting steps, we calculated the TST rate constants for the reactions for the temperature range of 200-500 K. At 298 K the rate constant (s-1) for the dissolution of neutral species was found to be several orders of magnitude smaller than the rate-limiting steps for the protonated and deprotonated species. The values of the rate constants were used in the rate law expression to calculate the overall dissolution rate (mol m-2 s-1) at a given pH. The calculated rates were compared to previously reported experimental and theoretical rates and were found to be in good agreement over 2-12 pH range.

AB - In this computational study, we present the dissolution rates for quartz as a function of pH at 298 K. At any given pH, the dissolution of the quartz surface depends on the distribution of protonated, deprotonated, or neutral species. The dissolution mechanism for each of these three species was investigated by ab initio electronic structure calculations to obtain the reaction profile. Using the barrier height along with the partition functions for the transition state and the reactants in the rate-limiting steps, we calculated the TST rate constants for the reactions for the temperature range of 200-500 K. At 298 K the rate constant (s-1) for the dissolution of neutral species was found to be several orders of magnitude smaller than the rate-limiting steps for the protonated and deprotonated species. The values of the rate constants were used in the rate law expression to calculate the overall dissolution rate (mol m-2 s-1) at a given pH. The calculated rates were compared to previously reported experimental and theoretical rates and were found to be in good agreement over 2-12 pH range.

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